Salmonella Genomic Islands and Antibiotic Resistance in Salmonella Enterica

Abstract

Antibiotic resistance in several Salmonella enterica serovars that cause gastrointestinal disease in humans is due to a set of related genomic islands carrying a class 1 integron, which carries the resistance genes. Salmonella genomic island 1 (SGI1), the first island of this type, was found in S. enterica serovar Typhimurium DT104 isolates, which are resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides and tetracycline. Several Salmonella serovars and Proteus mirablis have since been shown to harbor SGI1 or related islands carrying various sets of resistance genes and some distinct groups have emerged. SGI1 is an integrative mobilizable element and can be transferred experimentally into Escherichia coli. However, within serovars, isolates recovered from different parts of the world appear to be clonal, indicating that SGI1 movement may be rare. Potential reservoirs in food-producing animals or in ornamental fish have been identified for some serovars.

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

“…This element was first identified in Salmonella serovar Typhimurium DT104 but has since then been detected in many other serovars, including Salmonella serovars Agona, Albany, Cerro, Derby, Dusseldorf, Emek, Haifa, Infantis, Kentucky, Kiambu, Kingston, Meleagridis, Newport, Paratyphi B, and Tallahassee (413)(414)(415). In the classic SGI-1, a 14-kb region bracketed by two integron structures within this chromosomal element contains the antimicrobial resistance genes contributing to its ACSSuT properties: bla PSE-1 conferring resistance to ampicillin, floR to chloramphenicol and florfenicol, aadA2 to streptomycin, sul1 to sulfonamides, and tetG to tetracycline (416).…”

Molecular Characteristics of Salmonella Genomic Island 1 in Proteus mirabilis Isolates from Poultry Farms in China

“…The MDR region is a complex class 1 integron named In104 (4), containing five antibiotic resistance genes conferring resistance to ampicillin (Ap), chloramphenicol (Cm) and florfenicol (Ff), streptomycin (Sm) and spectinomycin (Sp), sulfonamides (Su), and tetracycline (Tc) (i.e., ApCmFfSmSpSuTc resistance phenotype) (3). SGI1 variants predominantly result from insertion sequence, homologous recombination, transposition, and loss or exchange of gene cassettes within the MDR region (5).…”

Salmonella Pathogenicity Islands

“…Virülans faktörleri, bakterinin organizmaya adezyonu, kolonizasyonu, invazyonu, immün sistemden kaçışı ve toksin üretimi gibi özellikleri sağlayan ürünleri kapsamaktadır. Bu adacıklar sayesinde Salmonella türleri makrofajlar, dendritik ve epitelyal hücreleri enfekte edebilmektedir [7][8][9] . SPA'nın varlığı veya yokluğu Salmonella serotipleri arasında farklılıklar gösterir.…”

“…SPA'nın varlığı veya yokluğu Salmonella serotipleri arasında farklılıklar gösterir. Bazı patojenite adaları Salmonella cinsi içinde korunmuş olarak bulunurken, bazıları belirli serotipler için özgüldür; bu nedenle konakçı adaptasyonu, patojenite ve oluşturulan enfeksiyonun şiddeti açısından serotipler arasın-da farklılıklar bulunmaktadır 4,6,7,10 . Bugüne kadar birçok virülan Salmonella tipinde tanımlanan en önemli gen kümeleri 12 SPA içinde yer almaktadır 4,11 (Tablo I).…”